Conducting Gel Polymer Research Articles

Effect of the progressive addition of 1-ethyl-3-methylimidazolium tetrafluoroborate as ionic liquid solvent for designing potassium ion conducting polymer gel electrolyte

Effect of the progressive addition of 1-ethyl-3-methylimidazolium tetrafluoroborate as ionic liquid solvent for designing potassium ion conducting polymer gel electrolyte

Effect of Nanosized Al2O3 Dispersion on the Structural and Electrochemical Properties of PMMA/TEGDME-Based Mg-Ion Conducting Polymer Gel Electrolyte

Effect of Nanosized Al2O3 Dispersion on the Structural and Electrochemical Properties of PMMA/TEGDME-Based Mg-Ion Conducting Polymer Gel Electrolyte

In-situ cured gel polymer/ecoflex hierarchical structure-based stretchable and robust TENG for intelligent touch perception and biometric recognition

Gel-based sensors for next generation touch panels have been acknowledged for their exceptional sensitivity and flexibility. However, these sensors typically depend on a metal grid connection, which is susceptible to structural deformation under heavy stress applications and necessitates external power. Here, we report a novel in-situ cured gel polymer electrode-based triboelectric nanogenerator (GPE-TENG) that is stretchable, semi-transparent, and durable, designed to enable a self-powered touch panel for intelligent touch perception. The in-situ curing of the hierarchical structure of the ionic polymer gel encapsulated within the ecoflex ensures robust adhesion of the ionic conductive polymer gel (PEO/LiTFSI) to the ecoflex layers, addressing the issue of delamination in TENG components under mechanical stress. As a result, the GPE-TENG demonstrates high durability, enduring under stretching of approximately 375 % and sustaining heavy mechanical deformations (under folding, twisting, and rolling) over a long period (approximately 2 months) without loss of functionality. Remarkably, the GPE-TENG exhibits outstanding energy harvesting capabilities with a peak power density of 0.36 W m-2. Notably, the GPE-TENG generates electrical signals through simple device stretching, thus serving as a self-powered wearable sensor for human activity monitoring. Moreover, a 9-digital arrayed (3 × 3) flexible, semi-transparent, and self-powered touch panel based on the GPE-TENG shows multifunctionality, including touch track/pattern recognition (i.e. touch and sliding mode) and a highly accurate (∼98 %) deep learning assisted smart biometric system for user identification.

Impact of Introducing EMIM-BF4 as Ionic Liquid Solvent on Electrochemical Properties of PVdF–HFP Based Sodium Ion Conducting Gel Polymer Electrolytes

Impact of Introducing EMIM-BF4 as Ionic Liquid Solvent on Electrochemical Properties of PVdF–HFP Based Sodium Ion Conducting Gel Polymer Electrolytes

Conducting Polymer-Based Gel Materials: Synthesis, Morphology, Thermal Properties, and Applications in Supercapacitors.

Despite the numerous ongoing research studies in the area of conducting polymer-based electrode materials for supercapacitors, the implementation has been inadequate for commercialization. Further understanding is required for the design and synthesis of suitable materials like conducting polymer-based gels as electrode materials for supercapacitor applications. Among the polymers, conductive polymer gels (CPGs) have generated great curiosity for their use as supercapacitors, owing to their attractive qualities like integrated 3D porous nanostructures, softness features, very good conductivity, greater pseudo capacitance, and environmental friendliness. In this review, we describe the current progress on the synthesis of CPGs for supercapacitor applications along with their morphological behaviors and thermal properties. We clearly explain the synthesis approaches and related phenomena, including electrochemical approaches for supercapacitors, especially their potential applications as supercapacitors based on these materials. Focus is also given to the recent advances of CPG-based electrodes for supercapacitors, and the electrochemical performances of CP-based promising composites with CNT, graphene oxides, and metal oxides is discussed. This review may provide an extensive reference for forthcoming insights into CPG-based supercapacitors for large-scale applications.

Effect of introducing different molecular liquid solvents on electrochemical and physical properties of sodium ion conducting polymer gel electrolytes

The current investigation presents comparative studies on the effect of introducing three different molecular liquid solvents, namely ethylene carbonate: diethyl carbonate (EC:DEC), tetra ethylene glycol dimethyl ether (TEGDME), and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) on the electrochemical and physical properties of sodium ion conducting polymer gel electrolytes (PGEs) containing sodium tetrafluoroborate (NaBF4) salt, and polyvinyllidene fluoride-co-hexafluoropropylene (PVdF-HFP) polymer. The PGE, which is optimized and contains the EC: DEC solvent, has an ionic conductivity of 8.9 × 10−4 S cm−1, electrochemical stability of 4.5 V and total ion transport number of 0.99 at 30 °C. Along with conductivity studies, the X-ray diffraction studies, show that the EC: DEC raises the entropy of the PGE to its maximum value. The thermogravimetric (TGA) and differential scanning calorimetry (DSC) investigations demonstrate that electrolyte with EC: DEC exhibits a weight loss of 13 % up to 200 °C and retain the gel phase up to 140 °C. The optimized electrolyte holds promise for forthcoming sodium based electrochemical devices.

Neural network inspired bionic ordered structure polyaniline gel for wearable sensor

In recent years, remarkable progress has been made in the research and development of traditional conductive polymer gel wearable sensors. However, it is still a challenge to achieve high sensitivity and mechanical strength at the same time due to the influence of the characteristics of conductive material in gels. Herein, inspired by human neural network, a novel biomimetic ordered polyaniline conductive gel is presented with stable conductivity (18.04 S/m), excellent sensitivity (GF of 3.53) under the condition of high elongation (stretching of 400 %-500 %), good mechanical properties, biocompatibility, and anti-freezing performance. This conductive gel is composed of maleic anhydride modified γ-cyclodextrin, polyaniline, and polyacrylamide. Modified γ-cyclodextrin can be firmly fixed on the polyacrylamide skeleton of the gel through chemical bonds. The aniline is evenly distributed in the hydrophobic cavity of modified cyclodextrin through hydrophobic interaction, and an ordered polyaniline network with γ-cyclodextrins as a physical crosslinking point is formed in the gel. This biomimetic ordered structure greatly improves the toughness and conductivity of the polyaniline network, which significantly enhances the sensing ability of polyaniline gels. This work is expected to provide a novel method for improving the mechanical and electrical properties of polyaniline gels and pave an avenue for the uniform dispersion of non-polar substances in polar gels.

Charge carrier dynamics and relaxation in highly conducting gel polymer electrolytes added with adiponitrile and dual redox

The fundamental understanding of the relationship between ion transport and segmental dynamics of polymer chains in polymer electrolytes is crucial for achieving high ionic conductivity at room temperature for technological applications in supercapacitors, batteries, etc. In this work, the ion dynamics and relaxation have been studied for gel polymer electrolytes (GPEs) containing P(VdF-HFP) as host polymer, adiponitrile as a plasticizer, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as ionic liquid, and diphenylamine and copper iodide redox additives as fillers. The crystallization temperature of the ionic liquid and the melting temperature of the plasticizer play important roles in ion dynamics. The highest room-temperature ionic conductivity (3.3 × 10−3 S/cm) was obtained for the GPE filled with dual redox additives. The broadband ac conductivity spectra have been analyzed by using the Universal Power law model coupled with the Poisson–Nernst–Planck (PNP) model. The solid–solid phase transition of the ionic liquid affects the grain and grain boundary regions of the GPEs due to the presence of redox fillers. The temperature dependence of the dielectric spectra of the GPEs containing redox fillers confirms the phase transition at the crystallization temperature. The electric modulus and dielectric spectra have been analyzed by using the Havrilliak–Nigami, Kohlrausch–Williams–Watts, and derivative dielectric constant functions. The scaling of ac conductivity and modulus spectra confirms a common ion conduction and relaxation mechanism for the GPEs. The influence of dual redox additives is clearly observed in the values of ionic conductivity, ion diffusivity, and relaxation time.

Direct-ink-write 3D printing of highly-stretchable polyaniline gel with hierarchical conducting network for customized wearable strain sensors

The development of direct-ink-write (DIW) 3D printing conducting polymer gels with remarkable mechanical properties, satisfactory conductivity, and customized three-dimensional structures is in high demand for next-generation wearable strain sensors, yet challenging due to the difficulty of preparing conducting polymer solutions with high concentrations. Herein, a novel cellulose nanocrystal (CNC)-regulated polyaniline (PANI) composite ink for DIW 3D printing customized wearable strain sensors with high stretchability and hierarchical conducting networks is fabricated. With the employment of CNC as a stabilizer to regulate the intermolecular interactions, the in-situ polymerized composite ink achieves well-dispersed PANI and abundant reversible intermolecular interactions, which is favorable for DIW 3D printing PANI composite gel with tailored planar patterns of high geometric accuracy. Benefiting from the hierarchical gel frameworks and abundant non-covalent interactions within the PANI-based composite ink, the PANI composite gel exhibits remarkable stretchability, promising low-temperature tolerance and excellent strain sensing performance. Due to its unique wavy mesh structure, the DIW-printed PANI composite gel-based wearable strain sensor is more sensitive and can accurately detect changes in the human body. This work aims to expedite the advancement of DIW printing conducting polymer gel for the development of personalized wearable strain sensors and advanced flexible electronics.

Perfluorinated Single-Ion Li+ Conducting Polymer Electrolyte for Lithium-Metal Batteries

Single-ion (Li+) conducting electrolytes with a high Li+ conductivity and transference number (LTN) are promising electrolyte candidates for eliminating the concentration polarization and inhibiting the growth of lithium dendrites in lithium-metal batteries at high power and energy densities. This study presents the synthesis and electrochemical characterization of an AB-type single-ion Li+ conducting polymer consisting of a perfluorinated lithium-salt monomer (A) covalently bonded to a polyethylene glycol monomer (B). An investigation into several plasticizers reveals that ether-based solvents with moderate dielectric constants significantly enhance the Li+ conductivity of single-ion (Li+) conducting gel polymer electrolytes (SIC-GPE) while also maintaining the mechanical integrity of SIC-GPE. The perfluorinated lithium-salt units with weakly coordinating anions provide the advantage of high Li+ conductivity (1.1 × 10–4 S cm–2) and transference number (0.92), while polyethylene glycol units contribute to high flexibility and enhance plasticizer wettability in the SIC-GPE. The interfacial stability and electrochemical performance of SIC-GPE are demonstrated in lithium-metal symmetric cells (maintaining stability for >1300 h at 1 mAh cm–2) and lithium-metal batteries (retaining 98% capacity after 200 cycles).

Impact of Ammonium Perchlorate Content on Electrically Controlled Gel Polymer Electrolyte Monopropellants

A group of five electrically controlled monopropellants were developed, and their fundamental rheological, electrochemical, thermal, and combustion properties were characterized. A baseline monopropellant was composed of lithium perchlorate complexed with polyethylene glycol to form an ionically conductive gel polymer electrolyte. Subsequent candidates were supplemented with varying amounts of ammonium perchlorate at a fixed polymer-to-oxidizer ratio to determine the effects of shifting oxidizer content on the fundamental properties. The ignition of the gel monopropellants using an applied DC voltage potential at atmospheric conditions was observed and determined to be primarily the result of an electrolytic reaction. Time-resolved infrared thermography confirmed initial heating and initiation of the gels at the cathode once temperatures had reached the decomposition temperature of the polymer. Fourier transform infrared analysis of collected residue from experiments halted before ignition revealed lithium deposition on the cathode, supporting electrochemical activity. It was found that the electrolytic ignition delay time was affected by the oxidizer content, the magnitude of the applied voltage, and the distance between the electrodes supplying the voltage.

Impact of Ionic Liquid Functionalized ZrO2 Nanoparticles on Poly (stearyl methacrylate) Grafted Poly (vinylidene fluoride‐co‐hexafluoropropylene) Based Highly Conductive Gel Polymer Electrolytes for Lithium‐Metal Batteries

AbstractIn this study, an organic‐inorganic hybrid polymer membrane is successfully designed and developed by grafting stearyl methacrylate (SMA) side chains onto the backbone of the P(VDF‐HFP) copolymer followed by blending with varying amounts of imidazolium ionic liquids functionalized ZrO2 nanoparticles. Different microporous gel polymer electrolytes (MGPEs) are prepared by immersing the membranes into a LiTFSI salt‐dissolved ionic liquid electrolyte. The membranes′ crystallinity, surface morphology, porosity, and thermal stability are investigated using various characterization techniques. The copolymer membrane blended with 60 wt % functionalized nanoparticles exhibits the highest porosity of 64.5 %, which allows it to achieve a maximum electrolyte uptake of 387 wt %. That enables the corresponding MGPE to achieve the highest room temperature lithium ion conductivity of ~5.34×10−3 S cm−1 with a wide electrochemical stability window and good electrochemical stability against Li metal. Leveraging these advantageous characteristics, the lab‐scale truly solid‐state Li|MGPE|LiFePO4 and Li|MGPE|LiNi0.8Mn0.1Co0.1O2 cells demonstrate excellent rate capability and reversible cycling stability while maintaining high specific capacities (up to 154 and 172 mAh g−1, respectively, at 0.5 C) with >99.0 % coulombic efficiency over 100 cycles. Such exceptional interfacial compatibility with both low‐ and high‐voltage cathodes establishes the applicability of these newly developed MGPEs in next‐generation all‐solid‐state lithium‐metal batteries.

Recent Advances and Developments in Injectable Conductive Polymer Gels for Bioelectronics.

Soft matter bioelectronics represents an emerging and interdisciplinary research frontier aiming to harness the synergy between biology and electronics for advanced diagnostic and healthcare applications. In this context, a whole family of soft gels have been recently developed with self-healing ability and tunable biological mimetic features to act as a tissue-like space bridging the interface between the electronic device and dynamic biological fluids and body tissues. This review article provides a comprehensive overview of electroactive polymer gels, formed by noncovalent intermolecular interactions and dynamic covalent bonds, as injectable electroactive gels, covering their synthesis, characterization, and applications. First, hydrogels crafted from conducting polymers (poly(3,4-ethylene-dioxythiophene) (PEDOT), polyaniline (PANi), and polypyrrole (PPy))-based networks which are connected through physical interactions (e.g., hydrogen bonding, π-π stacking, hydrophobic interactions) or dynamic covalent bonds (e.g., imine bonds, Schiff-base, borate ester bonds) are addressed. Injectable hydrogels involving hybrid networks of polymers with conductive nanomaterials (i.e., graphene oxide, carbon nanotubes, metallic nanoparticles, etc.) are also discussed. Besides, it also delves into recent advancements in injectable ionic liquid-integrated gels (iongels) and deep eutectic solvent-integrated gels (eutectogels), which present promising avenues for future research. Finally, the current applications and future prospects of injectable electroactive polymer gels in cutting-edge bioelectronic applications ranging from tissue engineering to biosensing are outlined.

Studies on potassium-ion conducting gel polymer electrolytes containing poly(vinylidene fluoride-hexafluoropropylene) polymer, potassium permanganate salt added with different plasticizers

Studies on potassium-ion conducting gel polymer electrolytes containing poly(vinylidene fluoride-hexafluoropropylene) polymer, potassium permanganate salt added with different plasticizers

A sodium ion conducting gel polymer electrolyte with counterbalance between 1-ethyl-3-methylimidazolium tetrafluoroborate and tetra ethylene glycol dimethyl ether for electrochemical applications.

For sodium batteries, the development of gel polymer electrolytes (GPEs) with remarkable electrochemical properties is in its early stage and persists to be a challenge. In this report we have synthesized a series of GPEs containing a poly(vinyllidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and poly (methyl methacrylate) (PMMA) as blend polymer, sodium perchlorate (NaClO4) as ion-conducting salt and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) and tetra ethylene glycol dimethyl ether (TEGDME) as molecular solvents. The counter balance between EMIM-BF4 and TEGDME is maintained by the electrolyte, which is formed through the optimal weight ratio of 2 : 1. GPEs have an advantageous set of properties, including stability window of 5 V, Na+ transference number of 0.20, and a room-temperature ionic conductivity of 5.8 × 10-3 S cm-1. According to enthalpy and entropy calculations, optimized GPE yields the highest amount of disorder or amorphicity and contributes to greatest conductivity. XRD analysis supports this argument. Thermal investigations show that optimized GPE may preserve gel phase up to 125 °C. The prototype sodium cell fabricated with optimize GPE has a specific capacity of 281 mA h g-1 and open circuit voltage of 2.5 V. The optimized GPE exhibits potential for future electrochemical applications.

Rapid self-healing, highly conductive and near-single-ion conducting gel polymer electrolytes based on dynamic boronic ester bonds for high-safety lithium metal batteries

Polymer electrolytes with high ionic conductivity and good self-healing capability are crucial for the development of lithium metal batteries with enhanced rate capability and safety. However, the application of self-healable polymer electrolytes is hindered by low ionic conductivity and slow self-healing speed. Herein, boronic ester based self-healing gel polymer electrolyte (PBAD-PEG) with high ionic conductivity and fast self-healing speed is developed. PBAD-PEG is fabricated by thiol-ene click reaction of a multifunctional monomer 2,2′-(1,4-phenylene)-bis (4-allyloxy-1,3,2-dioxaborolane) (PBAD) consisting of two dynamic boronic ester bonds, pentaerythritol tetra(3-mercaptopropionate) and polyethylene glycol diacrylate. Abundant reversible boronic ester bonds endow PBAD-PEG with good flexibility and excellent self-healing ability. PBAD-PEG can self-heal within 1 h at room temperature after damaged, which effectively restores the ionic conductivities and mechanical properties. PBAD-PEG possesses high ionic conductivity of 8.67 × 10−4 S cm−1 at 25 °C. Lewis acid-base interactions between anions and boron atoms of PBAD-PEG contributes to ultrahigh lithium-ion transference number of 0.71. PBAD-PEG exhibits significant resistance to the growth of Li dendrites. The fabricated LiFePO4/Li batteries with PBAD-PEG achieve significantly boosted cycle stability (capacity retention of 92.6 % after 150 cycles). More importantly, LiFePO4/Li cells with the healed PBAD-PEG also show excellent cycle performance.

Polymer gel electrolytes containing sodium salts with BF4−, ClO4− and CF3SO3− anions immobilized in TEGDME molecular liquid for sodium battery and electric double layer capacitor

The present study reports synthesis and analysis of different characteristics of sodium ion conducting polymer gel electrolytes (PGEs) containing sodium salts with BF4−, ClO4− and CF3SO3− anions dissolved in tetraethylene glycol dimethyl ether and immobilized in a copolymer matrix consisting of polymethyl methacrylate and poly(vinylidene fluoride-co-hexafluoropropylene). The PGE containing the NaBF4 salt could deliver an ionic conductivity of 1.4 × 10−3 S cm−1 at room temperature along with superior dielectric properties as compared to the electrolytes with NaClO4 and NaCF3SO3 salts. The feasibility of designing sodium-based batteries and EDLCs has been demonstrated using the optimized PGE containing NaBF4 salt. The prototype sodium‑sulfur (NaS) battery designed by utilizing the optimized PGE, sodium amalgam anode and sulfur cathode provides open circuit voltage of ∼2.4 V and initial discharge capacity of ∼163 mA h g−1 and 126 mA h g−1 at discharge currents of 33 mA g−1 and 66 mA g−1, respectively. This optimized PGE also demonstrate good compatibility with AC electrodes in electric double layer capacitor (EDLC) application and delivered a significant specific capacity ∼64 F g−1 at 0.5 mA cm−2 current.

In-Situ Crosslinked Single-Ion Conducting Gel Polymer Electrolyte for Lithium Metal Batteries

Lithium metal batteries (LMBs) have been considered as promising candidates for energy storage device due to their high energy density. However, high reactivity of lithium metal with liquid electrolyte and continuous growth of dendrite lead to degradation of cycle performance and cell failure. To overcome these problems, the strategy of employing gel polymer electrolytes (GPE) was investigated. GPE can effectively encapsulate organic solvents and facilitate uniform contact with electrodes. Both cations and anions migrate in conventional GPE, which gives rise to low Li+ ion transference number (tLi+). Low tLi+ causes inhomogeneous Li+ ion flux and continuous dendrite growth. Compared to conventional GPE, single-ion conducting gel polymer electrolytes (SIC-GPE) have superior tLi+ value close to unity, since the movement of anions is suppressed. In this work, we synthesized a novel sulfonamide based single-ion conductor and prepared the chemically crosslinked SIC-GPE. The electrolyte was obtained by a facile in-situ crosslinking that further improves interfacial contact with electrodes. The resulting SIC-GPE exhibited high tLi+, which led to homogeneous deposition of Li+ ion and enhanced electrochemical stability. The LMB cell employing SIC-GPE exhibited stable cycle performance, proving ability to suppress the growth of lithium dendrite.

Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium‐Ion Batteries

AbstractTunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high‐performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra‐thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol‐based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water‐binding capacity according to computational simulations. This strategy renders the electrolyte a room‐temperature ionic conductivity of 0.61 ± 0.12 mS cm−1 which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half‐cells in high specific capacity (161 mAh g−1 at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.

A Hybrid Strategy‐Based Ultra‐Narrow Stretchable Microelectrodes with Cell‐Level Resolution

AbstractStretchable ultra‐narrow (e.g., 10 µm in width) microelectrodes are crucial for the electrophysiological monitoring of single cells providing the fundamental understanding to the working mechanism of neuro network or other electrically functional cells. Current fabrication strategies either focus on the preparation of normal stretchable electrodes with hundreds of micrometers or millimeters in width by using inorganic conductive materials or develop conductive organic polymer gel for ultra‐narrow electrodes which suffer from low stretchability and instability for long‐term implantation, therefore, it is still highly desirable to explore bio‐interfacial ultra‐narrow stretchable inorganic electrodes. Herein, a hybrid strategy is reported to prepare ultra‐narrow multi‐channel stretchable microelectrodes without using photolithography or laser‐assisting etching. A 10 µm × 10 µm monitoring window is fabricated with enhanced interfacial impedance by the special rough surface. The stretchability achieves to 120% for this 10 µm‐width stretchable electrode. Supported by these superior properties, it is demonstrated that the stretchable microelectrodes can detect electrophysiological signals of single cells in vitro and collect electrophysiological signals more precisely in vivo. The reported strategy will open up the accessible preparation of the fine‐size stretchable microelectrode. It will significantly improve the resolution of monitoring and stimulation of inorganic stretchable electrodes.